<?php

    /**
     * PHPExcel_Worksheet_ColumnIterator
     * Copyright (c) 2006 - 2015 PHPExcel
     * This library is free software; you can redistribute it and/or
     * modify it under the terms of the GNU Lesser General Public
     * License as published by the Free Software Foundation; either
     * version 2.1 of the License, or (at your option) any later version.
     * This library is distributed in the hope that it will be useful,
     * but WITHOUT ANY WARRANTY; without even the implied warranty of
     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     * Lesser General Public License for more details.
     * You should have received a copy of the GNU Lesser General Public
     * License along with this library; if not, write to the Free Software
     * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
     * @category   PHPExcel
     * @package    PHPExcel_Worksheet
     * @copyright  Copyright (c) 2006 - 2015 PHPExcel (http://www.codeplex.com/PHPExcel)
     * @license    http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt    LGPL
     * @version    ##VERSION##, ##DATE##
     */
    class PHPExcel_Worksheet_ColumnIterator implements Iterator {
        /**
         * PHPExcel_Worksheet to iterate
         * @var PHPExcel_Worksheet
         */
        private $subject;
        /**
         * Current iterator position
         * @var int
         */
        private $position = 0;
        /**
         * Start position
         * @var int
         */
        private $startColumn = 0;
        /**
         * End position
         * @var int
         */
        private $endColumn = 0;

        /**
         * Create a new column iterator
         * @param    PHPExcel_Worksheet $subject     The worksheet to iterate over
         * @param    string             $startColumn The column address at which to start iterating
         * @param    string             $endColumn   Optionally, the column address at which to stop iterating
         */
        public function __construct(PHPExcel_Worksheet $subject = null, $startColumn = 'A', $endColumn = null) {
            // Set subject
            $this->subject = $subject;
            $this->resetEnd($endColumn);
            $this->resetStart($startColumn);
        }

        /**
         * (Re)Set the end column
         * @param string $endColumn The column address at which to stop iterating
         * @return PHPExcel_Worksheet_ColumnIterator
         */
        public function resetEnd($endColumn = null) {
            $endColumn       = ($endColumn) ? $endColumn : $this->subject->getHighestColumn();
            $this->endColumn = PHPExcel_Cell::columnIndexFromString($endColumn) - 1;
            return $this;
        }

        /**
         * (Re)Set the start column and the current column pointer
         * @param integer $startColumn The column address at which to start iterating
         * @return PHPExcel_Worksheet_ColumnIterator
         * @throws PHPExcel_Exception
         */
        public function resetStart($startColumn = 'A') {
            $startColumnIndex = PHPExcel_Cell::columnIndexFromString($startColumn) - 1;
            if ($startColumnIndex > PHPExcel_Cell::columnIndexFromString($this->subject->getHighestColumn()) - 1) {
                throw new PHPExcel_Exception("Start column ({$startColumn}) is beyond highest column ({$this->subject->getHighestColumn()})");
            }
            $this->startColumn = $startColumnIndex;
            if ($this->endColumn < $this->startColumn) {
                $this->endColumn = $this->startColumn;
            }
            $this->seek($startColumn);
            return $this;
        }

        /**
         * Set the column pointer to the selected column
         * @param string $column The column address to set the current pointer at
         * @return PHPExcel_Worksheet_ColumnIterator
         * @throws PHPExcel_Exception
         */
        public function seek($column = 'A') {
            $column = PHPExcel_Cell::columnIndexFromString($column) - 1;
            if (($column < $this->startColumn) || ($column > $this->endColumn)) {
                throw new PHPExcel_Exception("Column $column is out of range ({$this->startColumn} - {$this->endColumn})");
            }
            $this->position = $column;
            return $this;
        }

        /**
         * Destructor
         */
        public function __destruct() {
            unset($this->subject);
        }

        /**
         * Rewind the iterator to the starting column
         */
        public function rewind() {
            $this->position = $this->startColumn;
        }

        /**
         * Return the current column in this worksheet
         * @return PHPExcel_Worksheet_Column
         */
        public function current() {
            return new PHPExcel_Worksheet_Column($this->subject, PHPExcel_Cell::stringFromColumnIndex($this->position));
        }

        /**
         * Return the current iterator key
         * @return string
         */
        public function key() {
            return PHPExcel_Cell::stringFromColumnIndex($this->position);
        }

        /**
         * Set the iterator to its next value
         */
        public function next() {
            ++$this->position;
        }

        /**
         * Set the iterator to its previous value
         * @throws PHPExcel_Exception
         */
        public function prev() {
            if ($this->position <= $this->startColumn) {
                throw new PHPExcel_Exception("Column is already at the beginning of range (" . PHPExcel_Cell::stringFromColumnIndex($this->endColumn) . " - " . PHPExcel_Cell::stringFromColumnIndex($this->endColumn) . ")"
                );
            }
            --$this->position;
        }

        /**
         * Indicate if more columns exist in the worksheet range of columns that we're iterating
         * @return boolean
         */
        public function valid() {
            return $this->position <= $this->endColumn;
        }
    }
